How will things end?
Something I’m considering because I now have three series of The Door In Time partially done, and that’s one and some specials less than Russell T Davies before he handed over to Steven Moffat. Of course, I could double him (after all, I managed seven twenty-two-episode seasons of The Watch House) but I should at some point consider a final run.
Like a season finale but much more so. Smashing timelines, facing down armies, bringing back an ultimate villain despite their on-screen death or wheeling out some enormous new threat that’s been built up for the last few episodes.
Blow your budget, go bigger than ever, bring out a cast of thousands, threaten the Earth as a whole (while focusing on a few people we know and care about, naturally), toss in surreal new images like the Master turning transparent or Gallifrey looming over Earth, reveal secrets and hint at further mysteries about the PCs and NPCs, all possibly building up to an ending so over the top that it's best to retire.
Example: The Last Second
Searching for the Doctor, Emily finds herself in the space between times, London frozen in time. And the nightmarish black-cloaked figure of the half-dead Master hunting her, swooping over the still streets, surrounded by millions of unmoving people who cannot hear her calls for help. And the Doctor himself being used as a time engine to try and reverse time and shatter the universe.